The NORSOK standard D-10 rev.3 which is the basis for well integrity in drilling and well operations on the Norwegian Continental Shelf, including plug and abandonment procedures, states that “Control cables and lines shall be removed from areas where permanent well barriers are installed, since they may create vertical leak paths through the well barrier.” The main problem relates specifically to the insulation material of the control cables, which may degrade, creating void space between the plug material and the cable. Another problem is hydraulic lines, which are hollow and therefore cannot be a part of a permanent barrier. If the location for a permanent barrier contains control cables and lines, the practice today is to remove these by pulling out the whole production tubing which the cables and lines are attached to. This requires a drill rig onsite. Problems associated with this procedure are high time demands and cost, and potential safety issues.
WO10088542 aims to address these problems by forming a well barrier with a cable passing through the barrier and though fluid-tight pressure tested connectors. Cementation is performed around the connector and the cable is run on the outside of the tubing into a passageway through the connector. Thus, although the cable passes through the barrier, it is sealingly located in a passageway with pressure rated connectors provided at either end of the passageway. Of course, failure of the connectors could result in a fluid flow path through the barrier so the integrity of this system relies on the integrity of the connectors.
It is an aim of the present invention to provide an alternative method of plugging a well which helps to address the afore-mentioned problems.